The American Naturalist, Volumen30Essex Institute, 1896 |
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Página 230
... segments in the Hexapod body as twenty - one , of which six form the head ; three , the 1 1 Anhang . Abh . K. preuss . Akad . Wiss . , Berlin , 1895 . thorax ; and twelve , the abdomen . At some 230 [ March , The American Naturalist .
... segments in the Hexapod body as twenty - one , of which six form the head ; three , the 1 1 Anhang . Abh . K. preuss . Akad . Wiss . , Berlin , 1895 . thorax ; and twelve , the abdomen . At some 230 [ March , The American Naturalist .
Página 231
... segments . The frons , clypeus , labrum and com- pound eyes are parts of the first segment . The second segment bears the antennæ , the fourth the mandibles , and the fifth and sixth the two pairs of maxillæ . The hypopharynx does not ...
... segments . The frons , clypeus , labrum and com- pound eyes are parts of the first segment . The second segment bears the antennæ , the fourth the mandibles , and the fifth and sixth the two pairs of maxillæ . The hypopharynx does not ...
Página 248
... segment , " as is proved on the appearance of appendages . The ectodermal teloblasts divide twice as many times . Though these are the main points of the paper , a number of impor- tant observations and conclusions have been necessarily ...
... segment , " as is proved on the appearance of appendages . The ectodermal teloblasts divide twice as many times . Though these are the main points of the paper , a number of impor- tant observations and conclusions have been necessarily ...
Página 333
... segment ( at least in the Polydesmoidea ) . Moreover , all Diplopoda have apodous segments not differing otherwise from those which bear legs ; also all Diplopoda have segments which bear but one pair of legs , and yet have not been ...
... segment ( at least in the Polydesmoidea ) . Moreover , all Diplopoda have apodous segments not differing otherwise from those which bear legs ; also all Diplopoda have segments which bear but one pair of legs , and yet have not been ...
Página 334
... segment above the pedigerous lamina , indicating a pleural element about as broad as the lamina . That this is the pleural suture seems very probable , on theoretical grounds and more so that on the surface a special striæ followed the ...
... segment above the pedigerous lamina , indicating a pleural element about as broad as the lamina . That this is the pleural suture seems very probable , on theoretical grounds and more so that on the surface a special striæ followed the ...
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Página 911 - Its power of inducing fermentation in a solution of sugar was entirely destroyed, although no perceptible change in the appearance of the yeast cells could be detected under the microscope. This experiment was repeated several times, and always with the same result, although when the yeast was simply washed in water it readily induced fermentation.
Página 189 - Consequently, if the theory be true, it is indisputable that before the lowest Cambrian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Cambrian age to the present day; and that during these vast periods the world swarmed with living creatures.
Página 552 - Does the organism learn to make new adjustments, or to modify old ones, in accordance with the results of its own individual experience? If it does so, the fact cannot be due merely to reflex action in the sense above described, for it is impossible that heredity can have provided in advance for innovations upon, or alterations of, its machinery during the lifetime of a particular individual.
Página 431 - Their houses are mats or barks of trees, set on poles in the fashion of an English barn, but out of the power of the winds, for they are hardly higher than a man.
Página 169 - Illustrations of the dynamic metamorphism of anorthosites and related rocks in the Adirondacks...
Página 862 - Assistant Secretary of the Smithsonian Institution and Director of the National Museum, died in Washington, Sept.
Página 409 - Triarthrus. No traces of any special organs for this purpose have been found in this genus, and their former existence is very doubtful, especially in view of the perfection of details preserved in various parts of the animal. The delicacy of the appendages and ventral membrane of trilobites and their rarity of preservation are sufficient demonstration that these portions of the outer integument were of extreme thinness, and therefore perfectly capable of performing the function of respiration. Similar...
Página 544 - Naturalist. [July, ments) — but by the reinstatement of it by a discharge of the energies of the organism, concentrated as far as may be for the excessive stimulation of the organs (muscles, etc.) most nearly fitted by former habit to get this stimulation again (in which the " stimulation " stands for the condition favorable to adaptation).
Página 994 - We must therefore picture to ourselves a fertile plain occupying the whole of the Bristol Channel, and supporting herds of reindeer, horses, and bisons, many elephants and rhinoceroses, and now and then being traversed by a stray hippopotamus, which would afford abundant prey to the lions, bears, and hyaenas, inhabiting all the accessible caves, as well as to their great enemy and destroyer, man."* III.
Página 940 - In reviewing the results of these investigations and comparing one species with another, without losing sight of the fact that comparative good is not necessarily positive good, it appears that of 7 species considered the Downy Woodpecker is the most beneficial. This is due in part to the great number of insects it eats and in part to the nature of its vegetable food, which is of little value to man. Three-fourths of its food consists of insects, and few of these are useful kinds. Of grain, it eats...